1. Field of the Invention
The present invention relates to a motion sensing device and more particularly to a motion sensing device which detects motion such as inclination or swaying applied to a member, such as a vehicle, being measured.
2. Description of the Related Art
A conventional theft prevention device for vehicles detects swayings, inclinations, or impacts above a predetermined amplitude and sounds an alarm.
A motion sensing device of the prior art used in such a theft prevention device incorporates a pendulum containing a magnet and magnetic resistance elements mounted on a bracket directly under the pendulum in the vertical direction. The motion sensing device detects swaying, inclination, or impact on the basis of variations in the resistance of the magnetic resistance elements produced when the pendulum vibrates or inclines as a result of the vibration or inclination of a vehicle being measured.
However, the prior art motion sensing devices have a drawback in that the pendulum must initially be centered with respect to the magnetic resistance elements so that the center of the magnetic resistance elements oppositely face the pendulum each time the vehicle is parked on an incline.
The prior art motion sensing devices also have a drawback in that detection of an incline with high precision cannot be achieved, since the devices determine inclines based on the level of an analog signal produced by resistance variations in the magnetic resistance elements